I've set up two VMs on an "internal" (in VirtualBox meaning) network, one being a DNS server (dns1.example.com) and the other - a KDC and Kerberos admin server (kdc.example.com). The default and the only realm is EXAMPLE.COM. Both machines use freshly installed Debian Squeeze.
The problem: I can login via ssh on kdc.example.com from kdc.example.com, but I can't login via ssh from dns1.example.com.
On kdc.example.com, sshd in debug mode says:
Code:
debug1: Unspecified GSS failure. Minor code may provide more information
Wrong principal in request
debug1: Got no client credentials
debug3: mm_request_send entering: type 41
debug3: mm_request_receive entering
debug1: userauth-request for user tom service ssh-connection method gssapi-with-mic
debug1: attempt 2 failures 1
debug2: input_userauth_request: try method gssapi-with-mic
debug1: userauth-request for user tom service ssh-connection method gssapi-with-mic
debug1: attempt 3 failures 1
debug2: input_userauth_request: try method gssapi-with-mic
at which point the client is asked for a password. A tcpdump file processed by Wireshark shows there has been some exchange of crypted packets, but I can't deduct more as they are, well, crypted
. After 2 days of googling I'm stuck and would appreciate any help.
Even more would I appreciate any advice /links/hints on a general sane configuration debugging strategy, when it comes to Kerberos and friends. For example, I'm out of ideas where to look for what's wrong with 'Wrong principal', and what is that principal the server receives instead of the right one. Something tells me the real adventures are yet to come
.
Below are configs and diagnostic outputs. Hope I haven't forgot anything.
Code:
kdc:~# cat /etc/krb5kdc/kdc.conf
[kdcdefaults]
kdc_ports = 750,88
[realms]
EXAMPLE.COM = {
database_name = /var/lib/krb5kdc/principal
admin_keytab = FILE:/etc/krb5kdc/kadm5.keytab
acl_file = /etc/krb5kdc/kadm5.acl
key_stash_file = /etc/krb5kdc/stash
kdc_ports = 750,88
max_life = 10h 0m 0s
max_renewable_life = 7d 0h 0m 0s
master_key_type = des3-hmac-sha1
supported_enctypes = aes256-cts:normal arcfour-hmac:normal des3-hmac-sha1:normal des-cbc-crc:normal des:normal des:v4 des:norealm des:onlyrealm des:afs3
default_principal_flags = +preauth
}
Code:
kdc:~# kadmin.local -q 'listprincs'
Authenticating as principal root/admin@EXAMPLE.COM with password.
K/M@EXAMPLE.COM
host/dns1.example.com@EXAMPLE.COM
host/kdc.example.com@EXAMPLE.COM
host/localhost@EXAMPLE.COM
host/www.example.com@EXAMPLE.COM
kadmin/admin@EXAMPLE.COM
kadmin/changepw@EXAMPLE.COM
kadmin/history@EXAMPLE.COM
kadmin/kdc.example.com@EXAMPLE.COM
krbtgt/EXAMPLE.COM@EXAMPLE.COM
root/admin@EXAMPLE.COM
tom@EXAMPLE.COM
Code:
kdc:~# cat /etc/ssh/sshd_config |grep '^[^#]'
Port 22
ListenAddress 172.16.3.3
Protocol 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
UsePrivilegeSeparation yes
KeyRegenerationInterval 3600
ServerKeyBits 768
SyslogFacility AUTH
LogLevel INFO
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes
IgnoreRhosts yes
RhostsRSAAuthentication no
HostbasedAuthentication no
PermitEmptyPasswords no
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPIKeyExchange yes
GSSAPICleanupCredentials yes
X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
AcceptEnv LANG LC_*
Subsystem sftp /usr/lib/openssh/sftp-server
UsePAM yes
/etc/krb5.conf is identical on both kdc and dns1.
Code:
dns1:~$ cat /etc/krb5.conf
[libdefaults]
default_realm = EXAMPLE.COM
dns_lookup_realm = true
dns_lookup_kdc = true
forwardable = true
[realms]
EXAMPLE.COM={
admin_server = kdc.example.com
}
[domain_realm]
example.com = EXAMPLE.COM
.example.com = EXAMPLE.COM
[logging]
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmin.log
default = FILE:/var/log/krb5lib.log
The TGT is forwardable. On ssh client:
Code:
dns1:~$ klist -f
Ticket cache: FILE:/tmp/krb5cc_1000
Default principal: tom@EXAMPLE.COM
Valid starting Expires Service principal
01/03/12 20:00:03 01/04/12 06:00:03 krbtgt/EXAMPLE.COM@EXAMPLE.COM
renew until 01/04/12 20:00:00, Flags: FRIA
01/03/12 20:00:21 01/04/12 06:00:03 host/kdc.example.com@EXAMPLE.COM
renew until 01/04/12 20:00:00, Flags: FRAT
Keytab does also seem to be OK:
Code:
dns1:~# klist -k
Keytab name: WRFILE:/etc/krb5.keytab
KVNO Principal
---- --------------------------------------------------------------------------
5 host/dns1.example.com@EXAMPLE.COM
5 host/dns1.example.com@EXAMPLE.COM
5 host/dns1.example.com@EXAMPLE.COM
5 host/dns1.example.com@EXAMPLE.COM
DNS (incl. PTR, TXT, SRV) works as it should.
Code:
dns1:~# cat /var/cache/bind/db.example.com
$ORIGIN example.com.
$TTL 86400
@ IN SOA dns1.example.com. root.example.com. (
2012010301 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
86400 ) ; Negative Cache TTL
;
@ IN NS dns1.example.com.
dns1 IN A 172.16.3.2
www IN A 172.16.3.8
mail IN A 172.16.3.9
fed IN A 172.16.3.100
kdc IN A 172.16.3.3
;kds IN A 172.16.3.4
_kerberos TXT "EXAMPLE.COM"
krb IN CNAME kdc
_kerberos._udp SRV 0 0 88 kdc
_kerberos-master._udp SRV 0 0 88 kdc
_kerberos-adm._tcp SRV 0 0 749 kdc
_kpasswd._udp SRV 0 0 464 kdc
dns1:~# cat /var/cache/bind/db.3.16.172.in-addr.arpa
$ORIGIN 3.16.172.in-addr.arpa.
$TTL 86400
@ IN SOA dns1.example.com. root.example.com. (
2012010102 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
86400 ) ; Negative Cache TTL
;
@ IN NS dns1.example.com.
2 IN PTR dns1.example.com.
3 IN PTR kdc.example.com.
8 IN PTR example.com.
9 IN PTR mail.example.com.
Solved
